Clinical materials containing a small number of Vibrio should be inoculated into an enrichment medium before plating onto a selective medium, such as TCBS Agar. Alkaline Peptone Water is an excellent enrichment broth for Vibrio species.
The American Public Health Association recommends this medium for enrichment of Vibrio species from seafood, infectious materials, and other clinical specimens such as feces.
Principle of Alkaline Peptone Water
- The medium’s relatively high pH (approximately 8.4) provides a favorable environment for the growth of Vibrio species.
- Amino acids and other nitrogenous substances are provided by the peptic digestion of animal tissue.
- Sodium chloride maintains osmotic balance.
- Turbidity in tubes indicates growth when compared to an un-inoculated tube (control).
- Enrichment broth growth is used for plating on selective media. A pure culture is recommended for biochemical identification.
Composition of Alkaline Peptone Water
| Ingredients | Gms / Litre |
| Peptic digest of animal tissue | 10.000 |
| Sodium chloride | 10.000 |
| Final pH ( at 25°C) | 8.4±0.2 |
Type of specimen
- Seafood
- Infectious materials
- Other clinical specimens such as feces.
Preparation procedure
Label the ready to use bottle. Inoculate the sample and Incubate at specified temperature and time.
Quality Control
| Appearance | Sterile clear Alkaline Peptone Water in bottles. |
| Color and Clarity of prepared medium | Light yellow colored clear solution |
| Reaction | 8.20- 8.60 |
| Cultural Response | Cultural characteristics observed after incubation at 35-37°C for 18-24 hours. |
Cultural Response on Alkaline Peptone Water
| Vibrio cholerae ATCC 15748 | luxuriant |
| Vibrio parahaemolyticus ATCC 17802 | luxuriant |
Storage and Shelf Life
Store between 2-8°C. Use before expiry date on the label.
Reference
- Gilligan, Janda, Karmali and Miller, 1992, Cumitech 12A, Laboratory Diagnosis of Bacterial Diarrhea, Coord. Ed.
- Forbes B. A., Sahm A. S., and Weissfeld D. F., Bailey & Scotts Diagnostic Microbiology, 10th Ed., 1998, Mosby
- Isenberg, (Ed.), 1992, Clinical Microbiology Procedures Handbook, Vol. I, American Society for Microbiology. Washington, D.C.
